Resin composition for optical-semiconductor encapsulation

ABSTRACT

A photosemiconductor encapsulating resin composition, excellent in light transmittance, ultraviolet resistance and heat resistance, comprising the following component (A) and component (B):  
     (A): a (meth)acrylic polymer containing an epoxy group, and  
     (B): at least one hardener selected from the group consisting of the following components (b 1 ) to (b 4 ):  
     (b 1 ) a polyvalent carboxylic acid,  
     (b 2 ) a polyvalent carboxylic anhydride,  
     (b 3 ) a reaction product of a polyvalent carboxylic acid with a compound of the following general formula (B-1), and  
     (b 4 ) a reaction product of a polyvalent carboxylic anhydride with a compound of the following general formula (B-2)  
                 
 
     wherein R 1  to R 6  represent each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 3  and R 4  may be bonded to form an alkylene group having 1 to 8 carbon atoms; R 7  represents an alkylene group; a methylene group contained the alkylene group and the alkyl group represented by R 1  to R 7  may be substituted by an ether group and/or carbonyl group; Y 1  and Y 2  represent each independently an oxygen atom, or sulfur atom, is provided.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a photosemiconductorencapsulating resin composition, a photosemiconductor encapsulatinghardened substance obtained by hardening the composition, and aphotodiode encapsulated with the hardened substance.

[0003] 2. Description of Prior Art

[0004] Already known as the photosemiconductor encapsulating resincomposition used is, for example, a transparent resin compositioncomposed of an alicyclilc type epoxy resin and an acid anhydridehardener (JP-A No. 6-316626), and this publication specificallydiscloses a photosemiconductor encapsulating resin composition, furthercontaining a methacrylic acid-based phosphate for improving closeadherence with a photosemiconductor.

[0005] Recently, a light emitting diode emitting light of shortwavelength such as blue light, ultraviolet light and the like, and awhite color light emitting diode obtained by combining these lightemitting diodes with a fluorescent body are practically utilized. Toencapsulate these light emitting diodes, encapsulating resin compositionare required that transmittance for blue light to ultraviolet light ishigh and transmittance does not decrease by heat generation in operation(hereinafter, referred to as heat-resistance) or does not decrease bylight of short wavelength from a light emitting diode chip, namely, evenif irradiated with light of short wavelength having high energy such asblue light, ultraviolet light and the like for a long time, colorationdoes not occur(hereinafter, referred to as ultraviolet-resistance).

[0006] As the resin composition for encapsulating a light emittingdiode, a resin composition containing a non-aromatic type epoxy resin asan effective ingredient has been suggested, specifically, a lightemitting diode resin composition containing

[0007] 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate andmethylhexahydrophthalic anhydride as an effective ingredient has beendisclosed (JP-A No. 2000-196151).

[0008] The present inventors have investigated a transparent resincomposition composed of an alicyclic type epoxy resin and an alicycliccarboxylic anhydride, for example, a hardened substance of an epoxyresin composition containing

[0009] 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate andmethylhexahydrophthalic anhydride as an effective ingredient, used as aresin composition to seal a light emitting diode, and a problem has beenmade clear that a hardened substance of this composition is, directlyafter hardening, already colored though transparent, and when stored athigh temperature (150° C.) , the composition is further colored.

[0010] An object of the present invention is to provide aphotosemiconductor encapsulating resin composition giving a hardenedsubstance excellent in light transmittance from immediately afterhardening, excellent in light transmittance even if irradiated with bluelight or ultraviolet light for a long time or used at high temperaturefor a long time, namely, excellent in any of initial transmittance,ultraviolet-resistance and heat-resistance.

SUMMARY OF THE INVENTION

[0011] The present invention provides a photosemiconductor encapsulatingresin composition comprising the following component (A) and component(B):

[0012] (A): a (meth)acrylic polymer containing an epoxy group, and

[0013] (B): at least one hardener selected from the group consisting ofthe following components (b₁) to (b₄)

[0014] (b₁) a polyvalent carboxylic acid,

[0015] (b₂) a polyvalent carboxylic anhydride,

[0016] (b₃) a reaction product of a polyvalent carboxylic acid with acompound of the following general formula (B-1), and

[0017] (b₄) a reaction product of a polyvalent carboxylic anhydride witha compound of the following general formula (B-2)

[0018] wherein R¹ to R⁶ represent each independently a hydrogen atom oran alkyl group having 1 to 8 carbon atoms, R³ and R⁴ may be bonded toform an alkylene group having 1 to 8 carbon atoms; R⁷ represents analkylene group; a methylene group contained in the alkylene group andthe alkyl group represented by R¹ to R⁷ may be substituted by an ethergroup and/or carbonyl group; Y¹ and Y² represent each independently anoxygen atom, or sulfur atom.

[0019] The present invention also provides a hardened substance obtainedby hardening the above-mentioned resin composition; and photodiodeobtained by encapsulating a photosemiconductor selected from the groupconsisting of light emitting diode elements and photodiode elements withthe above-mentioned hardened substance.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] The component (A) in the present invention is a (meth)acrylicpolymer containing an epoxy group, and specifically exemplified are(meth)acrylic polymers containing an epoxy group obtained bypolymerizing at least one monomer selected from alkyl acrylates, alkylmethacrylates, acrylonitrile and methacrylonitrile with a monomer of thefollowing general formula (A-1):

R—X—CH₂E  (A-1)

[0021] wherein R represents an alkenyl group having 2 to 12 carbonatoms, X represents a carbonyloxy group or methyleneoxy group, and Erepresents an epoxy group selected from the following moieties:

[0022] As the monomer of the general formula (A-1), specifically listedare unsaturated glycidyl ethers such as allyl glycidyl ether,2-methylallyl glycidyl ether and the like; unsaturated glycidyl esterssuch as glycidyl acrylate, glycidyl methacrylate, glycidyl itaconate andthe like; saturated cyclic aliphatic type epoxy (meth)acrylates such as3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethylmethacrylate and the like.

[0023] As the monomer of the general formula (A-1) , two or moremonomers of the general formula (A-1) may be used.

[0024] As the monomer of the general formula (A-1), unsaturated glycidylesters and saturated cyclic aliphatic type epoxy (meth) acrylates arepreferable among others, and particularly, 3,4-epoxycyclohexylmethylacrylate and glycidyl methacrylate are suitable.

[0025] As the (meth) acrylic monomer used as the component (A), listedare, for example, alkyl (meth)acrylates having a linear alkyl grouphaving about 1 to 20 carbon atoms such as methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate and the like; alkyl(meth)acrylates having a branched alkyl group having about 3 to 20carbon atoms such as t-butyl acrylate, t-butyl methacrylate and thelike; alkyl (meth)acrylates having a saturated cyclic aliphatic alkylgroup having about 5 to 20 carbon atoms such as cyclohexyl acrylate,cyclohexyl methacrylate and the like; and (meth)acrylonitriles such asacrylonitrile, methacrylonitrile and the like.

[0026] As the (meth)acrylic monomer, two or more (meth)acrylic monomersmay be used.

[0027] As the (meth) acrylic monomer, alkyl (meth) acrylates arepreferable among others, and particularly, alkyl (meth)acrylates havinga linear or branched alkyl group having 1 to 4 carbon atoms, or alkyl(meth)acrylates having a saturated cyclic aliphatic alkyl group arepreferable.

[0028] The content of a structural unit derived from a (meth)acrylicmonomer in the component (A) is from about 0 to 95 mol %, preferablyfrom about 10 to 80 mol %.

[0029] In production of the component (A), an aliphatic monomer havingin the molecule one ethylenical double bond copolymerizable with(meth)acrylic monomers, different from (meth)acrylic monomers, may bepolymerized. Specific examples thereof include vinyl alkylates such asvinyl butyrate, vinyl propionate, vinyl pivalate, vinyl laurate, vinylisononoate, vinyl versatate and the like; vinyl halides such as vinylchloride, vinyl bromide and the like; vinylidene halides such asvinylidene chloride and the like.

[0030] The use amount of the aliphatic monomer in the component (A) isusually 10 parts by weight or less based on 100 parts by weight of thetotal amount of all monomers constituting a (meth)acrylic polymer, andsubstantially no use is preferable.

[0031] Mentioned as the method of producing the component (A) are, forexample,

[0032] a method in which monomers used and a radical generator are mixedin an organic solvent such as alcohols such as methanol, isopropanol andthe like; ketones such as acetone, methyl ethyl ketone, methyl isobutylketone and the like; esters such as ethyl acetate, butyl acetate and thelike; aromatic hydrocarbons such as toluene, xylene and the like,further, if necessary, a chain transfer agent is mixed with the mixture,and they are copolymerized at about 60 to 120° C.;

[0033] a method in which monomers used are fed to a reactor continuouslyand the mixture mentioned above is heated at 180-300° C. for 5-60minutes in the reactor in the absence or presence of polymerizationinitiator, followed by removing the reaction product from the reactorcontinuously, as described in JP-A-10-195111;

[0034] and other methods.

[0035] As the component (A), two or more (meth)acrylic polymerscontaining an epoxy group may be used.

[0036] The epoxy equivalent weight of a (meth)acrylic polymer containingan epoxy group is usually 128 g/equivalent or more, preferably fromabout 150 to 4500 g/equivalent.

[0037] As the (meth)acrylic polymer containing an epoxy group,commercially available products such as, for example, Blemmer CP-50M(glycidyl methacrylate·methyl methacrylate copolymer, manufactured byNOF Corp., and the like may be used.

[0038] Providing the hardened substance of the present invention is notcolored, an epoxy resin containing substantially no double bond in themolecule, different from a (meth)acrylic polymer containing an epoxygroup, may be mixed as the component (A).

[0039] Specifically listed as such an epoxy resin containingsubstantially no double bond in the molecule are hetero-cycle-containingepoxy resins, hydrogenated aromatic type epoxy resins, aliphatic typeepoxy resins (glycidyl ethers obtained from aliphatic alcohol andepihalohydrin), glycidyl esters of carboxylic acids (glycidyl estersobtained from aliphatic carboxylic acid and epihalohydrin or glycidylesters obtained from alicyclic carboxylic acid and epihalohydrin),saturated aliphatic type epoxy resins, spiro-ring-containing epoxyresins and the like.

[0040] As the hetero-cycle-containing epoxy resin, for example,hydantoin type epoxy resins, triglycidyl isocyanurate and the like arelisted.

[0041] As the hydrogenated aromatic type epoxy resin, for example,hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F typeepoxy resin, hydrogenated phenol novolak type epoxy resin, hydrogenatedcresol novolak type epoxy resin, hydrogenated biphenyl type epoxy resin,and the like are listed.

[0042] As the aliphatic type epoxy resin, for example, butyl glycidylether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidylether, cyclohexanedimethanol diglycidyl ether, polypropylene glycoldiglycidyl ether, trimethylolpropane triglycidyl ether and the like arelisted.

[0043] As the glycidyl ester of a carboxylic acid, for example, glycidylneodecanoate, diglycidyl hexahydrophtalate and the like are listed.

[0044] The saturated cyclic aliphatic type epoxy resin is an alicyclictype epoxy resin containing no double bond in the molecule, and listedas examples thereof are 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate of the following formula (A-2)

[0045] , ε-caprolactone-modified3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,bis(3,4-epoxycyclohexyl)adipate, 1,2:8,9-diepoxylimonene, and the like.

[0046] The content of an epoxy resin containing no carbon-carbon doublebond in the molecule in the component (A) is usually not more than theweight of a (meth)acrylic polymer containing an epoxy group.

[0047] The component (B) is at least one hardener selected from thegroup consisting of the following components (b₁) to (b₄):

[0048] (b₁) a polyvalent carboxylic acid,

[0049] (b₂) a polyvalent carboxylic anhydride,

[0050] (b₃) a reaction product of a polyvalent carboxylic acid with acompound of the following general formula (B-1), and

[0051] (b₄) a reaction product of a polyvalent carboxylic anhydride witha compound of the following general formula (B-2)

[0052] wherein R¹ to R⁶ represent each independently a hydrogen atom oran alkyl group having 1 to 8 carbon atoms, R³ and R⁴ may be bonded toform an alkylene group having 1 to 8 carbon atoms; R⁷ represents analkylene group; a methylene group contained in the alkylene group andthe alkyl group represented by R¹ to R⁷ may be substituted by an ethergroup and/or carbonyl group; Y¹ and Y² represent each independently anoxygen atom, or sulfur atom.

[0053] The component (b₁) is a compound having about 2 to 22 carbonatoms containing two or more free carboxyl groups in the molecule, andspecific examples thereof include aliphatic poly-valent carboxylic acidssuch as succinic acid, adipic acid, azelaic acid, sebacic acid,decamethylenedicarboxylic acid, dodecenylsuccinic acid,ethyloctadecanedioic acid and the like; aromatic poly-valent carboxylicacids such as phthalic acid, isophthalic acid, terephthalic acid,trimellitic acid, pyromellitic acid, 4,4′-benzophenonetetracarboxylicacid, 3,3′,4,4′-oxydiphthalic acid, 3,3′,4,4′-biphenyltetracarboxylicacid, phenyloctadecanedioic acid and the like, alicyclic poly-valentcarboxylic acids such as hexahydrophthalic acid,methyltetrahydrophthalic acid, methylhexahydrophthalic acid,5-norbornane-2,3-dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid,methylnorbornane-2,3-dicarboxylic acid,methylnorbornene-2,3-dicarboxylic acid,1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid,5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylicacid, 5-(2,5-dioxotetrahydro-3-furanyl)norbornane-2,3-dicarboxylic acid,and the like; acrylic resins obtained by polymerizing (meth)acrylicacid; maleated polybutadiene resin and the like.

[0054] The component (b₂) is an intra-molecular acid anhydride and/orinter-molecular acid anhydride of the component (b₁) , and specificexamples thereof include aromatic poly-valent carboxylic anhydrides suchas phthalic anhydride, tetrabromophthalic anhydride, tetrahydrophthalicanhydride, pyromellitic anhydride, 4,4′-benzophenonetetracarboxylicdianhydride, 3,3′,4,4′-oxydiphthalic dianhydride,3,3′,4,4′-biphenyltetracarboxylicdianhydride, ethylene glycolbistrimellitate (manufactured by New Japan Chemical Co., Ltd., tradename: TMEG), glycerol tristrimellitate (manufactured by New JapanChemical Co., Ltd., trade name: TMTA) and the like; alicyclicpoly-valent carboxylic anhydrides such as hexahydrophthalic anhydride,methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride,5-norbornane-2,3-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylicanhydride, methylnorbornane-2,3-dicarboxylic anhydride,methylnorbornene-2,3-dicarboxylic anhydride, Diels-Alder reactionproducts of maleic anhydride with a C₁₀ diene (manufactured by JapanEpoxy Resin, YH-306 and the like),1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic anhydride,5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylicanhydride, 5-(2,5-dioxotetrahydro-3-furanyl)norbornane-2,3- dicarboxylicanhydride, and the like; aliphatic poly-valent carboxylic anhydridessuch as dodecenylsuccinic anhydride, polyadipic anhydride, polyazelaicanhydride, polysebacic anhydride, poly(ethyloctadecanedioic) anhydride,poly (phenyloctadecanedioic) anhydride and the like; etc.

[0055] As the component (b₂), intra-molecular acid anhydrides arepreferable among others, and particularly, intra-molecular acidanhydrides of alicyclic poly-valent carboxylic acids are preferable, andof them, alicyclic carboxylic anhydrides containing substantially nodouble bond in the molecule such as hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, norbornane-2,3-dicarboxylicanhydride, methylnorbornane-2,3-dicarboxylic anhydride,5-(2,4-dioxotetrahydro-3-furanylmethyl)norbornane-2,3-dicarboxylicanhydride and the like are preferable.

[0056] The component (b₃) is a reaction product of the above-mentionedpoly-valent carboxylic acid (b₁) and a compound of the general formula(B-1), in which a free carboxylic group in (b₁) is protected by thegeneral formula (B-1). Here, listed as examples of the compound of thegeneral formula (B-1) are aliphatic vinyl ether compounds such as methylvinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinylether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinylether, cyclohexyl vinyl ether and the like and aliphatic vinyl thioethercompounds obtained by substituting an ether group in the above-mentionedcompounds by a thio ether group, further, cyclic vinyl ether compoundssuch as 2,3-dihydrofuran, 2,5-dihydrofuran, 3,4-dihydro-2H-pyran,3,4-dihydro-2-methoxy-2H-pyran, 3,4-dihydro-6-methyl-2H-pyran-2-one,5,6-dihydro-4-methoxy-2H-pyran, 3,4-dihydro-2-ethoxy-2H-pyran and thelike and cyclic vinyl thioether compounds obtained by substituting anether group in the above-mentioned compounds by a thio ether group, andthe like.

[0057] The component (b₄) is a reaction product of the above-mentionedpoly-valent carboxylic anhydride (b₂) and a compound of the generalformula (B-2) , in which an acid anhydride group in (b₂) is ring-openedand protected by the general formula (B-2). Here, listed as examples ofthe compound of the general formula (B-2) are trimethylene glycoldivinyl ether, ethylene glycol divinyl ether, polyethylene glycoldivinyl ether, butanediol divinyl ether, pantanediol divinyl ether,hexanediol divinyl ether, 1,4-cyclohexanedimethanol vinyl ether, vinyletherified compound of hydroquinone, vinyl etherified compound ofbisphenol A, vinyl etherified compound of bisphenol F, divinylthioethers obtained by substituting an ether group in these compoundswith a thio ether group.

[0058] As the component (B) used in the photosemiconductor encapsulatingresin composition of the present invention, the component (b₂) ispreferable among others.

[0059] The content of the component (B) in the resin composition differsdepending on the kinds of (b₁) to (b₄) and in the case of (b₁), thecontent of a free carboxyl group in (b₁) is preferably from about 1.0 to3.0 mol, more preferably from about 1.6 to 2.4 mol based on 1 mol of thetotal amount of epoxy groups contained in the component (A) , and in thecase of (b₂) , the content of an acid anhydride group (—CO—O—CO—) in(b₂) is preferably from about 0.5 to 1.5 mol, more preferably from about0.8 to 1.2 mol based on 1 mol of the total amount of epoxy groupscontained in the component (A). In the case of (b₃) , the content of anester group obtained by reaction with (B-1) is preferably from about 1.0to 3.0 mol, more preferably from about 1.6 to 2.4 mol based on 1 mol ofthe total amount of epoxy groups contained in the component (A), and inthe case of (b₄) , the content of an ester group obtained by reactionwith (B-2) is preferably from about 1.0 to 3.0 mol, more preferably fromabout 1.6 to 2.4 mol based on 1 mol of the total amount of epoxy groupscontained in the component (A).

[0060] The component (B) may contain a hardening accelerator, ifnecessary. As the hardening accelerator, for example, tertiary amines,tertiary amine salts, quaternary ammonium salts, imidazole compounds,diazabicycloalkene compounds and salts thereof, phosphine compounds,quaternary phosphonium salts, boron compounds, alcohols, metal salts,organic metal complex salts and the like are listed.

[0061] Here, as the tertiary amine, for example, triethanolamine,tetramethylhexanediamine, triethylenediamine, dimethylaniline,dimethylaminoethanol, diethylaminoethanol,2,4,6-tris(dimethylaminomethyl)phenol, N,N′-dimethylpiperazine,pyridine, picoline, benzyldimethylamine and2-(dimethylamino)methylphenol and the like are listed, and as thetertiary amine salt, 2-ethylhexanoate salt, octylate salt of tertiaryamine, and the like are listed.

[0062] As the quaternary ammonium salts, for example,dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride,benzyldimethyltetradecylammonium chloride and stearyltrimethylammoniumchloride, and those obtained by substituting the above-mentionedchloride by a bromide or iodide, and the like are listed.

[0063] As the imidazole compound, for example,1-benzyl-2-phenylimidazole, 2-methylimidazole, 2-undecylimidazole,2-ethylimidazole, 1-benzyl-2-methylimidazole,1-cyanoethyl-2-undecylimidazole and the like are listed.

[0064] As the diazabicycloalkene compound and salt thereof, for example,1,8-diazabicyclo(5,4,0)undec-7-ene, 1,5-diazabicyclo(4,3,0)non-5-ene,and phenol salts, octylate salts, p-toluenesulfonate salts, formatesalts, orthophthalate salts and tetraphenylborate salts thereof, and8-benzyl-1-aza-8-azoniadiazabicyclo(5.4.0)undec-7-ene tetraphenylborateand the like are listed.

[0065] As the phosphine compound, for example, triphenylphosphine,tri-n-butylphosphine, tri-n-octylphosphine, tritolylphosphine,tricyclohexylphosphine, tri-p-methoxyphenylphosphine,tris-(2,6-dimethoxyphenyl)phosphine and the like are listed.

[0066] As the quaternary phosphonium salt, for example,tetra-n-butylphosphonium bromide, tetra-n-butylphosphoniumbenzotriazolate, tetra-n-butylphosphonium tetrafluoroborate,tetra-n-butylphosphonium tetraphenylborate, tetraphenylphosphoniumbromide, methyltriphenylphosphonium bromide, ethyltriphenylphosphoniumbromide, ethyltriphenylphosphonium iodide, ethyltriphenylphosphoniumacetate, n-butyltriphenylphosphonium bromide, benzyltriphenylphosphoniumchloride, tetraphenylphosphonium tetraphenylborate and the like arelisted.

[0067] As the boron compound, for example, tetraphenylboron salts suchas triethyleneamine tetraphenylborate, N-methylmorpholinetetraphenylborate and the like are listed.

[0068] As the alcohols, for example, ethylene glycol, glycerins and thelike are listed.

[0069] As the hardening accelerator, two or more hardening acceleratorsmay be used.

[0070] As the hardening accelerator, quaternary phosphonium salts,imidazole compounds, diazabicycloalkene compounds and salts thereof arepreferable, among others.

[0071] For further improving the heat-resistance of a hardened substanceobtained from the photosemiconductor encapsulating resin composition ofthe present invention, it is recommendable to allow the composition tocontain antioxidant as an additive.

[0072] As the antioxidant, for example, (C) phenol-based antioxidants,(D) sulfur-based antioxidants, phosphorus-based antioxidants and thelike are listed.

[0073] As the phenol-based antioxidant (C) used in the presentinvention, for example, phenol-based antioxidants of the followinggeneral formula (C-1):

[0074] wherein n represents an integer of 1 to 22, are listed, andparticularly, phenol-based antioxidants having a carbon number n of fromabout 8 to 18 are suitable.

[0075] The content of the component (C) in the resin composition of thepresent invention is preferably from about 0.03 to 3parts by weight,more preferably from about 0.1 to 1 part by weight based on 100 parts byweight of the total amount of the component (A) and the component (B).

[0076] As the sulfur-based antioxidant (D) used in the presentinvention, for example, compounds of the following general formula(D-1):

[0077] wherein m represents an integer of 10 to 22, are listed, andparticularly, sulfur-based antioxidants in which m represents an integerof 12 to 19 are suitable.

[0078] The content of the component (D) in the resin composition of thepresent invention is preferably from about 0.03 to 3 parts by weight,more preferably from about 0.1 to 1 part by weight based on 100 parts byweight of the total amount of the component (A) and the component (B).

[0079] As the antioxidant, (C) phenol-based antioxidants, and (D)sulfur-based antioxidants are preferable, and particularly, it ispreferable to used (C) and (D) together.

[0080] The photosemiconductor encapsulating resin composition of thepresent invention may contain additives such as a mold releasing agent,silane coupling agent, stress-releasing agent, filler, plasticizer,de-foaming agent, thixotrope agent, dye, light scattering agent,ultraviolet absorber and the like, in an amount not deteriorating lighttransmittance, heat-resistance and ultraviolet-resistance of theresulting hardened substance.

[0081] As the method of producing a photosemiconductor encapsulatingresin composition, for example, when the component (A), component (B)and additives and the like are mainly in the form of solid, listed are amethod in which the component (A) , component (B) and additives and thelike are finely ground, then, mixed; a method in which the component(A), component (B) and additives and the like are melt kneaded in akneader; a method in which the component (A), component (B) andadditives and the like are dissolved in a solvent and uniformly stirredand mixed, then, the solvent is removed, and when the component (A)component (B) and additives and the like are mainly in the form ofliquid, listed are a method in which these are stirred and mixed; amethod in which the component (A), component (B) and additives and thelike are dissolved in a solvent and uniformly stirred and mixed, then,the solvent is removed, and other methods.

[0082] When the resulted resin composition is solid at normaltemperature, it may be further crushed and tabletted.

[0083] The resin composition of the present invention is usually curedby heating at the temperature from 80 to 200° C., preferably from 100 to180° C., more preferably from 120 to 200° C. for from about 0.2 to24hours. In the case of hardening, the step cure that combined two ormore steps of different conditions is also possible.

[0084] The hardened substance of the present invention is a thusobtained hardened substance of a resin composition. The initialtransmittance of the hardened substance is usually about 70% or more. Amore preferred hardened substance having the initial transmittance ofabout 75% or more can be obtained by using an alicyclic carboxylicanhydride containing substantially no double bond in the molecule as thecomponent (B).

[0085] Here, for obtaining the initial transmittance, a resincomposition is hardened and cooled to room temperature, and the resultedhardened substance is controlled to have a thickness of 2 mm, and withintwo days after cooling, the transmittance along the thickness directionat a wavelength of 370 nm is measured.

[0086] The hardened substance of the present invention is excellent inultraviolet-resistance and heat-resistance.

[0087] The hardened substance of the present invention usually has atransmittance in an ultraviolet resistance test of about 40% or more.Here, the ultraviolet-resistance test indicates a test in which ahardened substance having a thickness controlled at 2 mm is irradiatedwith light having a light quantity of 0.55 W/m² at 340 nm, underconditions of 40° C. and 50% RH, for 300 hours, then, the transmittancealong the thickness direction at a wavelength of 370 nm is measured.

[0088] The hardened substance of the present invention usually has atransmittance in a. heat resistance test of about 40% or more. Theheat-resistance test indicates a test in which a hardened substancehaving a thickness controlled at 2 mm is stored for 72 hours under acondition of 150° C., then, the transmittance along the thicknessdirection at a wavelength of 370 nm is measured.

[0089] When the transmittance after the ultraviolet resistance test andthe heat resistance test is about 40% or more, it means that colorationby ultraviolet and heat is prevented. A hardened substance having thistransmittance of 50% or more is particularly preferable. Such a hardenedsubstance having the transmittance of 50% or more can be obtained byusing an alicyclic carboxylic anhydride containing substantially nodouble bond in the molecule as the component (B) , using togetherquaternary phosphonium salts, imidazole compounds, diazabicycloalkenecompounds and salts thereof as the hardening accelerator, and adding aphenol-based antioxidant (C) and/or sulfur-based antioxidant (D) as theantioxidant.

[0090] The glass transition temperature of the hardened substance of thepresent invention is usually about 130° C. or more. When the glasstransition temperature is 130° C. or more, a tendency of more excellentheat-resistance is preferably observed.

[0091] The photodiode of the present invention is the one obtained by,for example, encapsulating a photosemiconductor such as a light emittingdiode element, photodiode element and the like with the hardenedsubstance of the present invention.

[0092] As the method of producing a photodiode, listed are, for example,a method in which a photosemiconductor is equipped with an electrodesuch as a lead line and the like if necessary, subsequently, thephotosemiconductor is encapsulated with the resin composition of thepresent invention and hardened according to a mold method such astransfer molding, casting and the like; a method in which aphotosemiconductor is mounted on a substrate, and this is encapsulatedwith the resin composition of the present invention and hardened, andother methods.

[0093] On the photodiode of the present invention, a light emitting bodydiffering from a photosemiconductor, such as a fluorescent bodies andthe like may be mounted.

[0094] The hardened substance obtained by hardening thephotosemiconductor encapsulating resin composition of the presentinvention is excellent in light transmittance for visible light,ultraviolet light and the like, and even if irradiated with light ofshort wavelength having high energy such as blue light, ultravioletlight and the like, for a long time, coloration is little, and lighttransmittance is excellent. Further, even if used at high temperaturefor a long time, the photosemiconductor encapsulating resin compositionof the present invention is excellent in light transmittance.

[0095] Since the resin composition of the present invention give ahardened substance having such excellent properties, the resincomposition can be used in transparent electric and electronic partencapsulating materials such as a light emitting diode and the like, andin transparent paints, transparent adhesives, materials substituted forglass, and the like.

[0096] The following examples will illustrate the present inventionfurther in detail, but do not limit the scope of the invention. Partsand % in examples are by weight unless otherwise stated.

[0097] <Method of Measurement of Physical Properties of HardenedSubstance>

[0098] (1) Initial Transmittance

[0099] A resin composition was hardened, and when cooled to roomtemperature, or within two days from cooling, the transmission spectrumof a hardened substance having a thickness of 2 mm was measured by aspectrophotometer V-560 manufactured by Nippon Bunko K. K., and thetransmittance at a wavelength of 370 nm was calculated.

[0100] (2) Transmittance after Stored at High Temperature

[0101] A hardened substance was stored for 72 hours in an convectionoven, then, the transmittance at a wavelength of 370 nm was measuredaccording to the same manner as in (1).

[0102] (3) Transmittance after Irradiation with Ultraviolet Light

[0103] A hardened substance was irradiated with light having a lightquantity of 0.55 W/m² at 340 nm, under conditions of 40° C. and 50% RH,for 300 hours, using ATLAS Ci4000 Xenon Weather-Ometer, then, thetransmittance at a wavelength of 370 nm was measured according to thesame manner as in (1).

[0104] (4) Glass Transition Temperature (Tg)

[0105] Measurement was conducted under conditions of a temperatureraising rate of 10° C./min. and a load of 10 g using TMA-100Thermomechanical Analyzer manufactured by Seiko Instruments Inc., andthe inflection point of a TMA curve was read and used as the glasstransition temperature (Tg).

EXAMPLE 1

[0106] A hardener was produced by adding 1 part of U-CAT 5003(quaternary phosphonium bromide, manufactured by SAN-APRO Ltd.) as ahardening accelerator to 100 parts of HN-5500 (methylhexahydrophthalicanhydride, manufactured by Hitachi Chemical Co., Ltd.) as a component(B).

[0107] 55 parts of the above-mentioned hardener component and 100 partsof Blemmer CP-50M (glycidyl methacrylate-methyl methacrylate copolymer,Mw=10000, epoxy equivalent weight=310 g/equivalent, Tg=70° C.,manufactured by NOF Corp.) as a component (A) were dissolved in 100parts of acetone, and uniformly mixed, then, acetone was distilled offby a vacuum drier, to obtain a photosemiconductor encapsulating resincomposition which was solid at room temperature. In the procedure, themolar ratio of epoxy groups to acid anhydrides was 1/1.

[0108] This resin composition was placed on a glass plate heatedpreviously at 100° C., and sandwiched with a separate glass plate heatedpreviously at 100° C., via a 2 mm spacer, and fixed by a clip,consequently, the resin composition was melted and molded into a platehaving a thickness of 2 mm. While being fixed by a clip, the resincomposition was hardened at 100° C. for 2 hours, subsequently, at 120°C. for 2 hours, to give a hardened substance having a thickness of 2 mm.

[0109] The results of measurement of physical properties of the hardenedsubstance are shown in Table 1.

EXAMPLE 2

[0110] A resin composition was obtained in the same manner as in Example1 except that the hardening accelerator was changed totetra-n-butylphosphonium bromide (manufactured by HOKKO CHEMICALINDUSTRY CO., LTD., TBP-BB).

[0111] This resin composition was hardened under press with a heat pressat 100° C. for 2 hours, then, hardened for 2 hours in a convection ovenof 120° C., to obtain a hardened substance having a thickness of 2 mm.The results of measurement of physical properties of the hardenedsubstance are shown in Table 1.

EXAMPLE 3

[0112] A resin composition and hardened substance were obtained in thesame manner as in Example 2 except that 0.5 parts of a phenol-basedantioxidant of the following formula (C-2) was added based on 100 partsof the resin composition in Example 2. The results of measurement ofphysical properties of the hardened substance are shown in Table 1.

EXAMPLE 4

[0113] A resin composition and hardened substance were obtained in thesame manner as in Example 2 except that 0.25 parts of a phenol-basedantioxidant of the formula (C-2) and 0.25 parts of a sulfur-basedantioxidant of the following formula (D-2) were added based on 100 partsof the resin composition in Example 2. The results of measurement ofphysical properties of the hardened substance are shown in Table 1.

COMPARATIVE EXAMPLE 1

[0114] 92 parts of the hardener component obtained in Example 1 wasadded to 100 parts of Epothoto YD-128M (bisphenol A diglycidyl ether,epoxy equivalent weight=185, manufactured by Tohto Kasei Co., Ltd.) as acomponent (A), and they were stirred and mixed, to obtain a resincomposition which is in the form of solution at room temperature. Inthis operation, the molar ratio of epoxy groups to acid anhydrides was1/1. Two glass plates were fixed via a 2 mm spacer to give a mold whichwas pre-heated at 100° C. A resin composition was injected into themold, then, hardened at 100° C. for 2 hours, subsequently, at 120° C.for 2 hours, to give a hardened substance having a thickness of 2 mm.

[0115] The results of measurement of physical properties of the hardenedsubstance are shown in Table 1.

COMPARATIVE EXAMPLE 2

[0116] 75 parts of Epothoto YD-128M and 25 parts of Celloxide 2021 P(3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, epoxyequivalent weight=134, manufactured by Daicel Chemical Industries, Ltd.)were mixed and used as a component (A) . This mixture (component (A))had an epoxy equivalent weight of 169.

[0117] 100 parts of this component (A) and 100 parts of the hardenercomponent obtained in Example 1 were stirred and mixed, to obtain aresin composition which is in the form of solution at room temperature.In this operation, the substance ratio (equivalent) of epoxy groups toacid anhydrides was 1/1. Subsequently, the resin composition was moldedand hardened in the same manner as in Comparative Example 1, to give ahardened substance having a thickness of 2 mm.

[0118] The results of measurement of physical properties of the hardenedsubstance are shown in Table 1.

COMPARATIVE EXAMPLE 3

[0119] 127 parts of the hardener component obtained in Example 1 wasadded to 100 parts of Celloxide 2021 P as a component (A) , and theywere stirred and mixed, to obtain a resin composition which is in theform of solution at room temperature. In this operation, the molar ratioof epoxy groups to acid anhydrides was 1/1. Subsequently, the resincomposition was molded and hardened in the same manner as in ComparativeExample 1, to give a hardened substance having a thickness of 2 mm.

[0120] The results of measurement of physical properties of the hardenedsubstance are shown in Table 1.

COMPARATIVE EXAMPLE 4

[0121] 81 parts of the hardener component obtained in Example 1 wasadded to 100 parts of HBPADGE (hydrogenated bisphenol A diglycidylether, epoxy equivalent weight=210, manufactured by MaruzenPetrochemical Co., Ltd.) as a component (A) , and they were stirred andmixed, to obtain a resin composition which is in the form of solution atroom temperature. In this operation, the molar ratio of epoxy groups toacid anhydrides was 1/1. Subsequently, the resin composition was moldedand hardened in the same manner as in Comparative Example 1, to give ahardened substance having a thickness of 2 mm.

[0122] The results of measurement of physical properties of the hardenedsubstance are shown in Table 1. TABLE 1 Example Comparative example 1 23 4 1 2 3 4 Trans- (1)  76  78  80  79  71  67  67  73 mit- ∘ ∘ ∘ ∘ ∘ xx ∘ tance (2)  51  50  62  69  50  41  39  39 (%) ∘ ∘ ∘ ∘ ∘ ∘ x x (3) 52  46  50  51  27  37  60  60 ∘ ∘ ∘ ∘ x x ∘ ∘ Tg (4) 145 138 138 138131 133 159 114 (° C.)

What is claimed is:
 1. A photosemiconductor encapsulating resincomposition comprising the following component (A) and component (B):(A): a (meth)acrylic polymer containing an epoxy group, and (B): atleast one hardener selected from the group consisting of the followingcomponents (b₁) to (b₄) (b₁) a polyvalent carboxylic acid, (b₂) apolyvalent carboxylic anhydride, (b₃) a reaction product of a polyvalentcarboxylic acid with a compound of the following general formula (B-1) ,and (b₄) a reaction product of a polyvalent carboxylic anhydride with acompound of the following general formula (B-2)

wherein R¹ to R⁶ represent each independently a hydrogen atom or analkyl group having 1 to 8 carbon atoms, R³ and R⁴ may be bonded to forman alkylene group having 1 to 8 carbon atoms; R⁷ represents an alkylenegroup; a methylene group contained in the alkylene group and the alkylgroup represented by R¹ to R⁷ may be substituted by an ether groupand/or carbonyl group; Y¹ and Y² represent each independently an oxygenatom, or sulfur atom.
 2. The resin composition according to claim 1wherein the component (A) is a (meth)acrylic polymer containing an epoxygroup obtained by polymerizing at least one monomer selected from alkylacrylates, alkyl methacrylates, acrylonitrile and methacrylonitrile witha monomer of the following general formula (A-1): R—X—CH₂-E  (A-1)wherein R represents an alkenyl group having 2 to 12 carbon atoms, Xrepresents a carbonyloxy group or methyleneoxy group, and E representsan epoxy group selected from the following moieties.


3. The resin composition according to claim 1 or 2 wherein the component(A) has an epoxy equivalent weight of 128 g/equivalent or more, and ahardened substance of the composition has a glass transition temperatureof 130° C. or more.
 4. The resin composition according to any of claims1 to 3 wherein. the component (b₂) is an alicyclic carboxylic anhydride.5. The resin composition according to any of claims 1 to 4 wherein thecomponent (b₂) is at least one alicyclic carboxylic anhydride selectedfrom the group consisting of hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, norbornane-2,3-dicarboxylicanhydride, methylnorbornane-2,3-dicarboxylic anhydride and5-(2,4-dioxotetrahydro-3-furanylmethyl)norbornane-2,3-dicarboxylicanhydride.
 6. The resin composition according to any of claims 1 to 5wherein the photosemiconductor encapsulating resin composition containsan antioxidant.
 7. The resin composition according to claim 6 wherein aphenol-based antioxidant (C) and/or sulfur-based antioxidant (D) iscontained as the antioxidant.
 8. The resin composition according toclaim 6 or 7 wherein the component (C) is a phenol-based antioxidant ofthe following general formula (C-1):

wherein n represents an integer of 1 to
 22. 9. The resin compositionaccording to claim 6 or 7 wherein the component (D) is a sulfur-basedantioxidant of the following general formula (D-1):

wherein m represents an integer of 10 to
 22. 10. A hardened substanceobtained by hardening the photosemiconductor encapsulating resincomposition of any of claims 1 to
 9. 11. The photosemiconductorencapsulating hardened substance according to claim 10 wherein thehardened substance having a thickness controlled at 2 mm shows aninitial transmittance along the thickness direction at a wavelength of370 nm of 70% or more, said hardened substance having a thicknesscontrolled at 2 mm shows, after an ultraviolet-resistance test in whicha hardened substance having a thickness controlled at 2 mm is irradiatedwith light having a light quantity of 0.55 W/m² at 340 nm, underconditions of 40° C. and 50% RH, for 300 hours, a transmittance alongthe thickness direction of 40% or more, and said hardened substance hasa glass transition temperature of 130° C. or more.
 12. A photodiodeproduced by encapsulating a photosemiconductor selected from the groupconsisting of light emitting diode elements and photodiode elements withthe hardened substance of claim 10 or 11.